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The master thesis report shows the process and result of the development of a optical cellular oxygen comsumption system for the diagnosis of Sepsis by using the fluoressing property of Protoporphyrin IX in the skin cells.

Traffic is increasing rapidly in terms of number of vehicles and also in axle loads. In order to maximize the availability of the pavement and to minimize hindrances to traffic because of maintenance works, long life pavements are needed. An asphalt pavement with self repairing capabilities is believed to be very useful to this respect. The self healing phenomenon of asphalt mixtures is known for many years by road engineers. Bituminous materials are expected to repair themselves during hot summers and (long) rest periods. However, the underlying mechanism is not well understood, and a proper way to measure it is not available. Research questions are: what is the self healing phenomenon, how to measure it effectively and efficiently and how to upgrade it if possible. In order to answer these questions, investigations were carried out in this thesis. This research focuses on understanding the self healing mechanism of bituminous materials and the effects of material modifications, by means of testing and modelling. The research started with a critical literature review. Preliminary research was conducted to explore possible self healing modifiers. Novel self healing modifiers like ionomers, supermolecular rubbers and nanoparticles were chosen and investigated. Upon analyzing the change of the material properties and the self healing capability due to modifications, it was observed however, that all the novel modifications used in this research are not quite beneficial for the self healing improvement of bituminous materials. A normal soft bitumen was observed to be the best healer among all the modified bitumens tested. Further research was conducted to assess the self healing capability of bituminous materials in further detail. Three test methods were developed to mimic the self healing phenomenon at different levels being from bitumen level to mixture level. The self healing phenomenon was directly related to a measurable crack. In each of the test methods used, cracks were produced first in a controlled way, and after that the healing process of these cracks was investigated. The test methods covered the following aspects: • A two-piece healing (TPH) test was developed to investigate the self healing behaviour of pure bitumen using the Dynamic Shear Rheometer (DSR). During the TPH test, the healing process was mimicked by pressing two pieces of bitumen together in a parallel-plate system. The development of the complex shear modulus during the closure of the gap width and during healing rest periods was monitored and used as a healing indicator. • A modified direct tension test was developed to assess the self healing capability of bituminous mastics. The cracks were first introduced via mechanical loading, and then healing rest periods were applied. After healing, the specimens were reloaded to determine the recovery of the material strength; this recovery was used as a healing indicator. This test can be used to investigate the self healing capability of an open crack with two total fractured surfaces and to determine the self healing capability of meso cracks. • A beam on elastic foundation test (BOEF) was developed to investigate the self healing phenomenon of asphalt mixtures with a notched asphalt concrete beam fully glued on a low modulus rubber foundation. After a crack is produced by imposing monotonic loading, the BOEF setup allows fully closure of the crack due to the confinement of the rubber foundation. After a healing period, the beams were reloaded and the stiffness recovery and strength recovery were used as indicators of healing. • The results of the various tests showed that the self healing capability of bituminous materials can be ranked successfully at different healing times, temperatures and damage levels. The self healing process of damage in bituminous materials consists of two main phases, namely the crack closure and the strength gain phase. The driving force can be either thermal (temperature) or mechanical (by confinement, pressure). The self healing capability is related to the viscosity of the bitumen, which increases with increasing healing time, temperature and when the crack size is very small. Finite element modelling was done to further investigate the self healing phenomenon in the tests. A smeared type cohesive zone model was used to model healing by defining the stiffness and strength recovery process. In this way, the self healing phenomenon was directly linked to a crack repairing process. Based on the research results, a better understanding of the self healing phenomenon was achieved. This thesis ends by discussing some important aspects of building a durable asphalt pavement with self healing capabilities. The self healing capability of an asphalt mixture should be optimized to obtain pavements with an enhanced durability.

It is a well known fact that asphalt mixtures have self healing capabilities. Yet most of the self healing investigations are carried out using complex and time consuming fatigue tests. In order to investigate the self healing capability in a simple and efficient manner, a beam on elastic foundation test setup (BOEF) is proposed in this paper. With a notched asphalt concrete beam fully glued on a low modulus rubber foundation, the BOEF setup is able to control the self healing process autonomously including crack closure and healing at different rest periods and temperatures. A load-crack opening displacement (COD) curve was used for characterizing the self healing capability of the monotonic response with a loading-healing reloading procedure. In addition, small numbers of dynamic loads were also applied to the BOEF setup under different cracking and healing conditions. An apparent modulus of the BOEF asphalt beam was obtained based on the dynamic response of the COD. The results indicate that the self healing capability which is obtained in the monotonic tests is dependent on the healing time and healing temperature. The healing temperature has the largest effect of the two. Most of the apparent modulus of the BOEF asphalt beam recovers at the beginning of the self healing process. The influences of healing time and temperature are limited. As a result, the BOEF setup is proven to be a potential tool for the self healing investigation of asphalt mixtures.

Self healing of asphalt mixes is known for more than four decades. However, it is a complex phenomenon which depends on the duration of the rest period, temperature, crack size, etc. In order to quantify the self healing behaviour of asphalt mixes, a test setup was proposed in this research using an asphalt beam on an elastic foundation. Within this setup, a notched asphalt beam was glued on a low modulus rubber foundation, and a symmetric monotonic load was applied with loading–unloading–healing–reloading cycles. The rubber foundation was used to avoid permanent deformation and to ensure a controllable healing process. Experimental results indicate that the beam on elastic foundation (BOEF) setup is capable for self healing investigations of asphalt mixes. The healing process was quantified by the recovery of the strength and the recovery of the crack opening displacement. The time, temperature and crack size dependency of the self healing behaviour were observed over the healing periods. Moreover, a self healing model was proposed to decompose the self healing phenomenon observed in the BOEF healing tests. It is shown that at the beginning of the healing period the delayed visco-elastic healing is the main reason of the recovery of the crack opening displacement and the viscous healing is important for healing after longer time/higher temperature.

The self-healing capability of bituminous materials has been known for many years. Researches were mostly focused on the self healing behaviour during load repetitions. The tests are either time consuming and/or complex. In this paper, a simple self healing test procedure is presented combining the fracture-healing-re-fracture test (FHR) with morphological observations. A fast displacement speed loading was applied first to produce a flat open crack with a crack width of 100–200 μm. Then the specimen was placed in a silicone rubber mould to heal. Various healing periods, temperatures and material modifications were applied. Fluorescence microscopy was used to observe the morphological change during the healing periods. After healing, the specimen was re-fractured under the same condition as the original fracture test. The experimental results indicate that the self healing capability, which was quantified by the re-fracture strength, increases with increasing healing time and increasing healing temperature. A strength recovery master curve at any healing temperature can be obtained through a timetemperature superposition principle. When comparing the strength recovery master curve with the morphological healing observation from fluorescence microscopy, the healing process observed in this paper is believed to be a viscosity driven process, consisting of two steps namely crack closure and strength gain. A Styrene-Butadiene-Styrene polymer modified bituminous mastic shows lower healing capability than a standard 70/100 penetration grade bituminous mastic. The test procedure proposed in this paper is proven to be simple and effective for evaluating and comparing the self healing capability of bituminous materials.

The traffic volume and the number of heavy vehicles are growing enormously nowadays. There is a need for designing a durable asphalt pavement with innovative technologies. Pavement structures and materials with self healing and self repairing capability are believed to be very useful in such a system. This paper is aiming to understand the self healing behaviour through mechanical testing and finite element modelling. Instead of a complex and time consuming fatigue involved self healing investigation, a more effective test method was developed for bituminous materials using the Direct Tension Test (DTT) with a monotonic loading-healing-reloading procedure. The results indicate that the self healing behaviour is a viscosity driven process and it is dependent on time, temperature and crack sizes. A visco-elastic coupled damage-healing (VEDH) model was developed using a smeared crack approach under finite element code FEMMASSE. By defining both visco-elastic and local damage-healing properties, the damage and healing behaviour of bituminous mastics can be simulated successfully. Based on the research findings, recommendations are also given for durable asphalt pavement with self healing technologies.